A good number of reports have been made on transition metal complexes useful for enantioselective synthesis reactions such as enantioselective hydrogenation, enantioselective isomerization, and enantioselective silylation reactions. Among these complexes, many complexes comprising a transition metal, e.g., ruthenium, palladium, and rhodium, coordinated with an optically active tertiary phosphine compound exhibit excellent catalytic performance as catalysts for enantioselective syntheses. In order to improve the catalytic performance, various phosphine compounds having a special structure have been developed to date as disclosed, e.g., in The Chemical Society of Japan (ed.), KAGAKU SOSETSU, Vol. 32, "YUKI KINZOKU SAKUTAI NO KAGAKU" , pp. 237-238 (1982).
In particular, 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (hereinafter abbreviated as BINAP) is one of excellent phosphine compounds, and rhodium complexes and ruthenium complexes using BINAP as a ligand have been respectively reported in JP-A-55-61937 and JP-A-61-63690 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
It has also been reported that rhodium or ruthenium complexes using 2,2'-bis[di-(p-tolyl)phosphino]-1,1'-binaphthyl as a ligand bring satisfactory results in enantioselective hydrogenation and enantioselective isomerization reactions as described in JP-A-60-199898 or JP-A-61-63690. However, these known phosphine complexes have been still unsatisfactory in terms of selectivity, conversion, or duration of activity depending on the purposed reaction mode or the reaction substrate.